Nathaniel D. Lambert

Understanding the immune response to seasonal influenza vaccination in older adults: a systems biology approach

Annual vaccination against seasonal influenza is recommended to decrease disease-related mortality and morbidity. However, one population that responds suboptimally to influenza vaccine is adults over the age of 65 years. The natural aging process is associated with a complex deterioration of multiple components of the host immune system. Research into this phenomenon, known as immunosenescence, has shown that aging alters both the innate and adaptive branches of the immune system. The intricate mechanisms involved in immune response to influenza vaccine, and how these responses are altered with age, have led us to adopt a more encompassing systems biology approach to understand exactly why the response to vaccination diminishes with age. Here, the authors review what changes occur with immunosenescence, and some immunogenetic factors that influence response, and outline the systems biology approach to understand the immune response to seasonal influenza vaccination in older adults.

The Impact of Immunosenescence on Humoral Immune Response Variation after Influenza A/H1N1 Vaccination in Older Subjects

Background Although influenza causes significant morbidity and mortality in the elderly, the factors underlying the reduced vaccine immunogenicity and efficacy in this age group are not completely understood. Age and immunosenescence factors, and their impact on humoral immunity after influenza vaccination, are of growing interest for the development of better vaccines for the elderly. Methods We assessed associations between age and immunosenescence markers (T cell receptor rearrangement excision circles – TREC content, peripheral white blood cell telomerase – TERT expression and CD28 expression on T cells) and influenza A/H1N1 vaccine-induced measures of humoral immunity in 106 older subjects at baseline and three timepoints post-vaccination. Results TERT activity (TERT mRNA expression) was significantly positively correlated with the observed increase in the influenza-specific memory B cell ELISPOT response at Day 28 compared to baseline (p-value=0.025). TREC levels were positively correlated with the baseline and early (Day 3) influenza A/H1N1-specific memory B cell ELISPOT response (p-value=0.042 and p-value=0.035, respectively). The expression and/or expression change of CD28 on CD4+ and/or CD8+ T cells at baseline and Day 3 was positively correlated with the influenza A/H1N1-specific memory B cell ELISPOT response at baseline, Day 28 and Day 75 post-vaccination. In a multivariable analysis, the peak antibody response (HAI and/or VNA at Day 28) was negatively associated with age, the percentage of CD8+CD28low T cells, IgD+CD27- naïve B cells, and percentage overall CD20- B cells and plasmablasts, measured at Day 3 post-vaccination. The early change in influenza-specific memory B cell ELISPOT response was positively correlated with the observed increase in influenza A/H1N1-specific HAI antibodies at Day 28 and Day 75 relative to baseline (p-value=0.007 and p-value=0.005, respectively). Conclusion Our data suggest that influenza-specific humoral immunity is significantly influenced by age, and that specific markers of immunosenescence (e.g., the baseline/early expression of CD28 on CD4+ and/or CD8+ T cells and T cell immune abnormalities) are correlated with different humoral immune response outcomes observed after vaccination in older individuals, and thus can be potentially used to predict vaccine immunogenicity.

Polymorphisms in HLA-DPB1 Are Associated With Differences in Rubella Virus–Specific Humoral Immunity After Vaccination

Vaccination with live attenuated rubella virus induces a strong immune response in most individuals. However, small numbers of subjects never reach or maintain protective antibody levels, and there is a high degree of variability in immune response. We have previously described genetic polymorphisms in HLA and other candidate genes that are associated with interindividual differences in humoral immunity to rubella virus. To expand our previous work, we performed a genome-wide association study (GWAS) to discover single-nucleotide polymorphisms (SNPs) associated with rubella virus-specific neutralizing antibodies. We identified rs2064479 in the HLA-DPB1 genetic region as being significantly associated with humoral immune response variations after rubella vaccination (P = 8.62 × 10(-8)). All other significant SNPs in this GWAS were located near the HLA-DPB1 gene (P ≤ 1 × 10(-7)). These findings demonstrate that polymorphisms in HLA-DPB1 are strongly associated with interindividual differences in neutralizing antibody levels to rubella vaccination and represent a validation of our previous HLA work.

Associations between race, sex and immune response variations to rubella vaccination in two independent cohorts

INTRODUCTION Immune response variations after vaccination are influenced by host genetic factors and demographic variables, such as race, ethnicity and sex. The latter have not been systematically studied in regard to live rubella vaccine, but are of interest for developing next generation vaccines for diverse populations, for predicting immune responses after vaccination, and for better understanding the variables that impact immune response. METHODS We assessed associations between demographic variables, including race, ethnicity and sex, and rubella-specific neutralizing antibody levels and secreted cytokines (IFNγ, IL-6) in two independent cohorts (1994 subjects), using linear and linear mixed models approaches, and genetically defined racial and ethnic categorizations. RESULTS Our replicated findings in two independent, large, racially diverse cohorts indicate that individuals of African descent have significantly higher rubella-specific neutralizing antibody levels compared to individuals of European descent and/or Hispanic ethnicity (p<0.001). CONCLUSION Our study provides consistent evidence for racial/ethnic differences in humoral immune response following rubella vaccination.

High-throughput assay optimization and statistical interpolation of rubella-specific neutralizing antibody titers.

ABSTRACT Rubella remains a social and economic burden due to the high incidence of congenital rubella syndrome (CRS) in some countries. For this reason, an accurate and efficient high-throughput measure of antibody response to vaccination is an important tool. In order to measure rubella-specific neutralizing antibodies in a large cohort of vaccinated individuals, a high-throughput immunocolorimetric system was developed. Statistical interpolation models were applied to the resulting titers to refine quantitative estimates of neutralizing antibody titers relative to the assayed neutralizing antibody dilutions. This assay, including the statistical methods developed, can be used to assess the neutralizing humoral immune response to rubella virus and may be adaptable for assessing the response to other viral vaccines and infectious agents.

Genome-wide SNP associations with rubella-specific cytokine responses in measles-mumps-rubella vaccine recipients

Genetic polymorphisms are known to affect responses to both viral infection and vaccination. Our previous work has described genetic polymorphisms significantly associated with variations in immune response to rubella vaccine from multiple gene families with known immune function, including HLA, cytokine and cytokine receptor genes, and in genes controlling innate and adaptive immunity. In this study, we assessed cellular immune responses (IFNγ and IL-6) in a cohort of healthy younger individuals and performed genome-wide SNP analysis on these same individuals. Here, we report the first genome-wide association study focused on immune responses following rubella vaccination. Our results indicate that rs16928280 in protein tyrosine phosphatase delta (PTPRD) and a collection of SNPs in ACO1 (encoding an iron regulatory protein) are associated with interindividual variations in IFNγ response to rubella virus stimulation. In contrast, we did not identify any significant genetic associations with rubella-specific IL-6 response. These genetic regions may influence rubella vaccine-induced IFNγ responses and warrant further studies in additional cohorts in order to confirm these findings.

The personal touch: strategies toward personalized vaccines and predicting immune responses to them

The impact of vaccines on public health and wellbeing has been profound. Smallpox has been eradicated, polio is nearing eradication, and multiple diseases have been eliminated from certain areas of the world. Unfortunately, we now face diseases such as hepatitis C, malaria or tuberculosis, as well as new and re-emerging pathogens for which we lack effective vaccines. Empirical approaches to vaccine development have been successful in the past, but may not be up to the current infectious disease challenges facing us. New, directed approaches to vaccine design, development, and testing need to be developed. Ideally these approaches will capitalize on cutting-edge technologies, advanced analytical and modeling strategies, and up-to-date knowledge of both pathogen and host. These approaches will pay particular attention to the causes of inter-individual variation in vaccine response in order to develop new vaccines tailored to the unique needs of individuals and communities within the population.

Taxa of the Nasal Microbiome Are Associated with Influenza-Specific IgA Response to Live Attenuated Influenza Vaccine

Live attenuated influenza vaccine (LAIV) has demonstrated varying levels of efficacy against seasonal influenza; however, LAIV may be used as a tool to measure interactions between the human microbiome and a live, replicating virus. To increase our knowledge of this interaction, we measured changes to the nasal microbiome in subjects who received LAIV to determine if associations between influenza-specific IgA production and the nasal microbiome exist after immunization with a live virus vaccine. The anterior nares of 47 healthy subjects were swabbed pre- (Day 0) and post- (Days 7 and 28) LAIV administration, and nasal washes were conducted on Days 0 and 28. We performed next-generation sequencing on amplified 16s rRNA genes and measured mucosal influenza-specific IgA titers via enzyme-linked immunosorbent assay (ELISA). A significant increase in alpha diversity was identified (Observed, CHAO, and ACE) between Days 7 vs 0 (p-values = 0.017, 0.005, 0.005, respectively) and between Days 28 vs 0 (p-values = 0.054, 0.030, 0.050, respectively). Several significant associations between the presence of different microbial species, including Lactobacillus helveticus, Prevotella melaninogenica, Streptococcus infantis, Veillonella dispar, and Bacteroides ovatus, and influenza-specific H1 and H3 IgA antibody response were demonstrated. These data suggest that LAIV alters the nasal microbiome, allowing several less-abundant OTUs to establish a community niche. Additionally, specific alterations in the nasal microbiome are significantly associated with variations in influenza-specific IgA antibody production and could be clinically relevant.

Associations between single nucleotide polymorphisms in cellular viral receptors and attachment factor-related genes and humoral immunity to rubella vaccination

Background Viral attachment and cell entry host factors are important for viral replication, pathogenesis, and the generation and sustenance of immune responses after infection and/or vaccination, and are plausible genetic regulators of vaccine-induced immunity. Methods Using a tag-SNP approach in candidate gene study, we assessed the role of selected cell surface receptor genes, attachment factor-related genes, along with other immune genes in the genetic control of immune response variations after live rubella vaccination in two independent study cohorts. Results Our analysis revealed evidence for multiple associations between genetic variants in the PVR, PVRL2, CD209/DC-SIGN, RARB, MOG, IL6 and other immune function-related genes and rubella-specific neutralizing antibodies after vaccination (meta p-value <0.05). Conclusion Our results indicate that multiple SNPs from genes involved in cell adhesion, viral attachment, and viral entry, as well as others in genes involved in signaling and/or immune response regulation, play a role in modulating humoral immune responses following live rubella vaccination.